Systems for water extraction

ABSTRACT

The present invention relates to a water extraction system comprising a flow cell comprising a membrane; said membrane comprising an active layer comprising immobilized aquaporin water channels and a support layer, and said membrane having a feed side and a non-feed side; and an aqueous source solution in fluid communication with the feed side of the membrane.

FIELD OF THE INVENTION

The present invention relates to a system for water extraction saidsystem comprising a flow cell housing a filter membrane, where saidmembrane has an active layer comprising immobilized aquaporin waterchannels, and a porous support layer, and where an aqueous sourcesolution is in fluid communication with said membrane. In addition, theinvention relates to systems for removal of contaminants from watersources, systems for generation of diluted nutrient solutions forirrigation purposes using fertilizer drawn forward osmosis, systems forconcentrating organic and/or inorganic solutes in aqueous solutions,water extraction systems using forward osmosis and/or reverse osmosis ingeneral, such as low pressure reverse osmosis, systems for pressureretarded osmosis, waste water or process water treatment includingextraction of water from used dialysate solutions, and combined systemsfor desalination and/or energy generation having low or zero carbonemission.

BACKGROUND OF THE INVENTION

Water is the most essential component of life. However, with the growingscarcity of clean water, more and more interest is being paid toextraction of clean water from seawater and industrial water and totreatment of industrial process water and difficult wastewater streams.There is also an interest in the possibility of gentle water extractionfrom valuable solutions—from food streams to solutions of proteins andpeptides or valuable small organic compounds.

Among different water purification techniques, reverse osmosis, forwardosmosis and nanofiltration have become popular for water extractionbecause of their effectiveness in removing low molecular weight solutes,such as small organic compounds and ions. However, these waterextraction techniques are still energy-intensive and not alwayssufficiently selective. Examples are contaminants, such as dissolvedboron compounds naturally present in seawater and in contaminatedgroundwater, and which can pose a problem in desalinated water forirrigation and drinking water, and arsenic compounds that are frequentlypresent in natural surface and ground water sources, e.g. in alluvialplains and moraine deposits.

Kim et al. 2012 studied boron rejection in various FO and RO waterfiltration experiments and found a maximum boron retention of about 50to 55% in FO mode. However, this low boron filtration efficiency maynecessitate several filtration cycles in order to obtain a desired lowboron content in the resulting filtrate. Thus it is crucial to developimproved water extraction systems, such as systems that are able toremove water contaminants, such as boron or arsenic, and preferably infew or only one filtration step(s). In addition, it is a purpose of theinvention to provide a water extraction system adapted for fertilizerdrawn forward osmosis (FDFO), where seawater, brackish water, impairedground or surface water or any other suitable water source can be usedas a feed solution and a concentrated inorganic plant nutrient solutionis used as a draw solution resulting in a final fertilizer solutionhaving a sufficiently low osmolality or boron content as to allow it tobe used as a liquid fertilizer, e.g. as irrigation water with addednutrients. Moreover, it is a purpose of the invention to provide a novelsystem for energy storage as well as a novel system for reuse of water,such as ultrapure water, in hemodialysis.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a water extractionsystem utilizing aquaporin water channels immobilized in or on asupported filter membrane, such as in the form of a supported orimmobilized liquid membrane formulation. With reference to FIG. 1 saidsystem comprises a flow cell (1) comprising a membrane (2) where saidmembrane comprises an active layer (3) comprising aquaporin waterchannels and a porous support layer (4), and said membrane having a feedside (5) and a non-feed side (6); and said system further comprising anaqueous source solution (7) in fluid communication with said feed side.The present invention provides a novel system for selective waterextraction, wherein a filter membrane incorporating aquaporin waterchannels, such as the aquaporin Z water channels, provide to the systemthe unique and selective water transporting properties of said channels,i.e. highly efficient water flux, high salt rejection, low energyconsumption in forward osmosis operation mode, high rejection of smallorganic and inorganic solutes, intrinsic low fouling propensity, androbust operation conditions, especially of the membranes used in thesystem.

Other objects of the invention will be apparent to the person skilled inthe art from the following detailed description and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a schematic diagram of the essential features of a waterextraction system, wherein: (1) is the flow cell; (2) is the membrane;and (7) is the aqueous source solution. FIG. 1B shows the embodimentwhere the active layer (3) is on the feed side (5) of the membrane andthe support layer (4) is on the non-feed side (6) of the membrane. TheFIG. 1B membrane configuration has shown higher rejection % of boroncontaining solutes in some experiments, cf. Example 1. FIG. 1C shows theembodiment where the support layer (4) is on the feed side (5) of themembrane and the active layer (3) is on the non-feed side (6) of themembrane.

FIG. 2 shows a schematic diagram of a Forward Osmosis (FO) system forwater extraction from a feed stream, wherein: (10) is the feed stream;(1) is the flow cell with the membrane (2); (11) is the concentratedfeed stream; (8) is the draw solution in fluid communication with thedraw side of the membrane; and (9) is a draw solution concentration unit(9).

FIG. 3 shows a schematic diagram of a Fertilizer Drawn Forward Osmosis(FDFO) desalination system, wherein: (10) is the feed stream, preferablyof non-potable water; (13) is the concentrated fertilizer solution; (1)is the flow cell with the membrane; (12) is the partly dilutedfertilizer solution which can be re-circulated to achieve higher degreeof dilution; (14) is the additional freshwater tank for final adjustmentof the degree of dilution of the fertilizer solution; (11) is theconcentrated feed stream, e.g. up-concentrated seawater; (15) is thediluted fertilizer solution ready for use.

FIG. 4 shows a schematic diagram of a Reverse Osmosis (RO) system,wherein: (18) is the feed tank; (16) is a pump; (17) is a valve; (19) isthe permeate and (20) is the permeate tank. The flow from the pumpthrough the flow cell and back to the valve is a pressurized flow.

FIG. 5 shows a schematic diagram of a Forward Osmosis (FO) system fordesalination with regeneration of the draw solution to extract theproduct water, wherein (21) is the feed stream, e.g. seawater; (1) isthe flow cell with the membrane (2); (22) is the concentrated feedstream; (23) is the concentrated draw solution; (8) the draw solution influid communication with the flow cell; (24) the diluted draw solution;(9) the draw solution recovery system; and (25) the desalinated productwater, free of draw solution solutes.

FIG. 6 shows a schematic diagram of a pressure retarded osmosis (PRO)system, wherein: (1) is the flow cell with the membrane (2); (26) is thefeed stream, e.g. fresh water or seawater having a lower osmolality thanthe draw stream; (16) is a pump; (27) is the feed water bleed; (28) isthe draw stream, e.g. seawater or brine; (29) is a pump; (30) is thediluted and pressurized draw stream; (31) is a turbine to generatepower; (32) and (34) are depressurized draw water; and (33) is apressure exchanger to assist in pressurizing the incoming draw stream.

FIG. 7 shows a schematic diagram of a FO concentrator, wherein (41) isthe base unit containing a flow inlet and flow outlet to ensure anoptimal draw solution flow profile beneath the membrane (45); (42) isthe disposable top unit; the membrane (45) is secured and sealed to thetop unit together with an additional seal (43) to the base unit; (44) isan optional flow generator to stir the solution in the top unit; (46) isan inline monitoring system to monitor and continuously display thedegree of concentration in the top unit feed solution, e.g. the volumeand weight can be inspected visually; (47) is the feedback loopmechanism designed to stop the concentration process once the desiredconcentration is reached; (48) is a pump to recirculate the drawsolution; and (49) is a disposable draw solution pouch containingcustomized draw solution for different concentration processes.

FIG. 8 shows a schematic diagram of a modified FO concentrator, wherein(41) is the base unit containing a customized flow inlet and flow outletto ensure an optimal draw solution flow profile beneath the membrane(45), the base unit contains a securing mechanism for the disposable topunit (42); (43) is an O-ring to secure and seal the flow cell; (44) isan optional flow generator to stir the solution in the top unit; (46) isan inline monitoring system to monitor and continuously display thedegree of concentration in the top unit feed solution; (47) is thefeedback loop mechanism designed to stop the concentration process oncethe desired concentration is reached; (48) is a pump to recirculate thedraw solution; and (49) is a disposable draw solution pouch containingcustomized draw solution for different concentration processes; and (50)is an optional mesh support above the membrane (45) to providestability.

FIG. 9 shows a schematic diagram of the top unit of the FO concentratorin FIG. 8 seen from above, wherein (51) are means for the clampingtogether of the top and the base units.

FIG. 10 shows a schematic diagram of the base unit of the FOconcentrator in FIG. 8 seen from above.

FIG. 11 shows a schematic diagram of a combination of a Reverse Osmosis(RO) system for storing energy from renewable sources by concentrationof a salt solution combined with a pressure retarded osmosis (PRO)system for creating energy by dilution of the concentrated solution,wherein (1) is the flow cell with the membrane (2); (61) is the saltsolution side; (62) is the desalted water side; (63) is the desaltedwater tank; (16) is a pump; (17) is a valve; (64) is the salt solutiontank; (31) is a turbine to generate power; (65) is an outlet ofdepressurized diluted salt solution; (66) is a return stream ofdepressurized diluted salt solution; and (67) is an inlet of fresh saltsolution.

DETAILED DESCRIPTION OF THE INVENTION

More specifically, the invention relates to systems for water extractionas detailed below.

Water Extraction System with Removal of Contaminants

The present invention relates to systems using RO and or FO for theremoval of contaminants, such as trace contaminants including heavymetals and toxic inorganic compounds, from water sources. Examplesinclude removal of boron contamination from fresh water sources to beused for various purposes where boron is unwanted, e.g. for humanconsumption. Boron is an especially troublesome contamination in seawater sources when these are used for desalination to produce irrigationwater and potable water. Existing technologies require two filtrationpasses in order to obtain sufficiently low boron concentration. Thesystem of the invention offers removal of up to about 65% of thedissolved boron in a fresh water source at about neutral pH after onlyone RO pass and up to about 75% removal during an FO process at neutralpH, cf. the Example 1 below. Another example is the removal of arseniccontamination where the system of the invention can remove about 100%after both RO and FO filtration, cf. Example 2 below.

Water Extraction System for Fertilizer Drawn Forward OsmosisDesalination (FDFO)

Recently, there has been increasing interest in substituting diminishingfreshwater sources with desalinated water for irrigation of crops, andfurther addition of diluted nutrient salt solutions to the irrigationwater (FDFO). However, there are disadvantages in connection with theuse of available FO membranes, such as the membranes that may beobtained from the Hydro well filter modules (Hydration TechnologiesInc.) the disadvantage being mainly the relatively large reverse saltflux (Js) of the nutrient salts, e.g. potassium chloride, where figuresas high as 59.58 g/m²h have been mentioned in the literature (0.222mmoles/m²s, Phuntsho et al. 2011) or 6.8 to 15.3 g/m² h (Achilli et al.2010 using a flat-sheet cellulose triacetate (CTA) membrane fromHydration Technology Innovations, LLC, Scottsdale, Ariz.). It isdesirable to have as low as possible a Js in order to minimize loss ofthe valuable nutrient ions. Herein we show that it is possible to obtainJs of less than 4 g/m² h in an FO system using a TFC-AqpZ membranes withamphiphile P8061 as vesicle forming substance (prepared according to theexperimental section below), a 2 M KCl solution as draw, and deionizedwater with 5 μM calcein as feed, cf. the table below:

Jw J_(s,total) R_(calcein) Run time Draw, FO chamber [L/m²h] [g/m²h] [%]Min 2M KCl, CF042 10.3 3.08 99.94 900 2M KCl, CF042 11.47 3.32 99.95 9002M KCl, CF042 10.87 3.91 99.95 900 2M KCl, CF042 12.56 3.69 99.97 900 2MKCl, CF042 11.87 3.03 99.78 900 2M KCl, CF042 10.32 3.49 99.96 900 2MKCl, CF042 10.86 3.36 99.94 900

The table clearly shows that a consistent low reverse salt flux ofaverage 3.41 [g/m²h] can be obtained for the potassium salt KCl.

In addition, the present invention provides a low-energy means ofreducing freshwater consumption in agriculture by as much as about 40%through the utilization of lower-grade or non-potable water suppliessuch as polluted groundwater, brackish water and even seawater. Thewater extraction system of the invention with its unique aquaporinmembrane, such as in the form of a TFC membrane as prepared according tothe experimental section herein, is used in combination with a liquidconcentrated fertilizer draw solution to selectively extract clean waterfrom the lower-grade water supplies herein utilized as feed source. Theend result is a diluted liquid plant nutrient solution, which requiresless freshwater to be ready for use for agricultural irrigation andfertilization. In the example below we describe how membrane tests haveshown proof-of-concept in the case where the lower-grade water supply isrelatively low-salinity of about 10 to 15 o/oo seawater from Øresund inDenmark.

A Water Extraction System with Separation of Urea from Urine in Space

We have together with scientists from the NASA Ames facilities in PaloAlto (CA, US) performed first real field tests with the systemcomprising an aquaporin membrane. Tests concluded that the waterextraction system comprising the specific TFC-aquaporin membranes showsuperior rejection values to urea (>90%) when compared to existingforward osmosis membranes, cf. Hill & Taylor (2012). The waterextraction system of the invention will contribute to the major effortof reducing the mass needed to transport into space on manned spacemissions, i.a. by re-circulating bodily fluids from the astronauts. Itwas concluded that a water extraction system according to the inventioncomes very close to fulfilling the requirements for a simple,lightweight and reliable system to extract potable water from bodyfluids in space.

In May 2012, scientists from Aquaporin A/S and NASA Ames successfullyrepeated testing at the NASA Ames facilities with up-scaledTFC-aquaporin membrane samples (500 cm²). The up-scaled membrane samplesperformed identically to the initial samples thus proving the stabilityof the membrane production protocols. Based on the successful secondtests, Aquaporin A/S and NASA Ames are investigating how to produce thefirst prototype system for yellow water re-use in space.

A Water Extraction System with Separation of Urea from RO Permeate inDairy Industries

Background: Many industrial effluents contain high concentrations ofcompounds including non-polar solutes such as urea, which are notremoved by de-ionized water processes or reverse osmosis membranes. Saidnon-polar solutes are often chemically stable, and therefore not easilydestroyed by UV sterilization processes. The state of the art treatmentof urea wastewaters generally involves two steps: first, the hydrolysisof urea into ammonia and carbon dioxide and, second, the elimination ofammonia. Current methods mostly rely on anaerobic conditions for thebiological treatment of high-strength urea wastewaters. However therequired nitrifying bacteria have slow growth rates, a small acceptablepH-range, and are often inhibited by other wastewater contaminants (e.g.dicyandiamide). An advantage of the present system is that it is basedon the use of a flow cell equipped with a membrane having immobilizedaquaporin water channels, said membranes have shown very high urearemoval in lab scale, cf. Example 7 below. This will eliminate the needfor bioreactor technology and in principle allow for simple retrofittingof existing unit operations (e.g. polishing steps) currently employed inurea removal.

The high rejection and water flux properties of the aquaporin membraneand the intrinsic low fouling propensity makes it feasible and valuableto employ these biomimetic membranes into large scale industrial systemsfor urea removal, where there is a potential for fouling and/or a needto up-concentrate small neutral solutes (e.g. urea)—not readilyachievable with current technology—membrane based or other. The highrejection towards urea enables the system of the invention to be usedfor treatment of wastewater streams containing high amounts of urea,such as is present in process water from dairies. In one embodiment ofthe water extraction system of the invention, the aquaporin membrane,such as a TFC-membrane comprising immobilized aquaporin water channels,will be used together with a high osmolarity draw solution (e.g.seawater e.g. from Kattegat) to extract close to urea-free water fromthe wastewater streams. This low-energy water extraction system willeffectively reduce disposal costs through wastewater volume reduction.

Water Extraction System for Up-Concentration of Solutes in a Wide Rangeof Aqueous Solutions by Forward Osmosis, Cf. FIG. 6

In this system a high osmolarity or osmolality draw solution, such asbrine, is used in combination with an aquaporin membrane, such as theTFC membrane prepared as described herein, to up-concentrate aqueoussolutions in a forward osmosis process. Aqueous solutions of interestinclude difficult wastewater streams, pharmaceutical and biologicalproduct solutions and liquid foodstuffs. An exemplary embodiment is asystem for up-concentration of organic molecules of a wide range ofmolecular sizes, such as amino acids and oligopeptides to proteinsincluding membrane proteins which are normally concentrated to adesirable degree by centrifugal concentrators, e.g. using PierceConcentrators that are available for 3K, 10K, 30K, and 100Kmolecular-weight cutoff (MWCO), and which concentrate and desaltbiological samples with polyether sulfone (PES)-membrane ultrafiltrationcentrifugal devices. Advantages of the system according to the inventioninclude a very gentle extraction of water, low peptide or protein loss,ability to concentrate a wide range of molecular sizes from amino acidsto small peptides to large membrane proteins, a concentration processthat is controllable and can be automated for high throughput incontrast to centrifugal concentrators presently on the market, oralternatively, concentrating the sample solution by vacuum drying, whichis, however, often followed by severe loss of sample material and inadditional contaminations. The system of the invention may be set upwith a concentrator cell with either fixed aquaporin membrane for singleuse or with a removable aquaporin membrane as shown in FIG. 8. Thus,where the aquaporin membrane can be removed, e.g. for cleaning, andrefitted into the cell, it is suggested that an EDTA or citric acidtreatment as described in examples 4 and 5 below could be applied to themembrane while preserving the water extracting properties of the system.

DEFINITIONS

“Feed solution” means a solution of solutes in water.

“Draw solution” means a solution of higher osmotic pressure, relative tothat of the feed solution. The draw solution may comprise a draw soluteselected from at least one of water-soluble inorganic chemicals andwater-soluble organic chemicals. The water-soluble inorganic chemicalsmay include at least one of Al₂(SO₄)₃, MgSO₄, Na₂SO, K₂SO₄, (NH₄)₂SO₄,Fe₂(SO₄)₃, AlCl₃, MgCl₂, NaCl, CaCl₂, NH₄Cl, KCl, FeCl₃, Al(N0₃)₃,Mg(NO₃)₂, Ca(NO₃)₂, NaNO₃, NO₃, NH₄HCO₃, KHCO₃, NaHCO₃, KBr and theirrelative hydrates; and wherein the water-soluble organic chemicalsinclude at least one of methanol, ethanol, acetone, glucose, sucrose,fructose, dextrose, chitosan, dendrimer and 2-methylimidazole-basedchemicals.

“Forward osmosis” (FO) is an osmotic process in which an osmoticpressure gradient across a semi-permeable membrane results in extractionof water from dissolved solutes. The driving force for inducing a netflow of water through the membrane is an osmotic pressure gradient froma draw solution of higher osmotic pressure relative to that of the feedsolution.

The term “assisted forward osmosis” (AFO) (or “pressure assisted forwardosmosis”, PAFO) as used herein refers to the concept of applying amechanical pressure to the feed side of the membrane to enhance thewater flux through synergising the osmotic and hydraulic driving forces.

“Reverse osmosis” (RO) is a process of extracting water through asemi-permeable membrane from a feed solution against a gradient ofosmotic pressure, by applying a mechanical pressure that is higher thanthe osmotic pressure of the feed solution.

“Semi-permeable membrane” is a membrane that will allow certainmolecules or ions to pass through it.

“Osmotic pressure” is the pressure that must be applied to prevent thenet flow of solvent through a semipermeable membrane from a solution oflower solute concentration to a solution of higher solute concentration.

The osmotic pressure of a solution depends on the amount of particles inthe solution. For an ideal solution the osmotic pressure is directlyproportional to the molality.

“Osmolality” is a measure of the moles (or osmoles) of osmotic activesolutes per kilogram of solvent, expressed as osmole/kg. The osmolalityof an ideal solution of a non-dissociated compound equals the molality.

Osmolality is typically measured by freezing point depression. A oneosmol/kg aqueous solution has a freezing point of −1.858° C. As anexample: a 1 mol solution of e.g. sugar in 1 kg of water lowers thefreezing point with 1.858° C. whereas the freezing point depression willbe obtained by 0.5 mol in 1 kg of water.

“Osmolarity” is a measure of the osmoles of solute per liter ofsolution.

The “osmotic pressure” can be calculated from the osmolality by usingthe formula:

${\pi ({bar})} = {{{osmolality}\left( \frac{osmole}{L} \right)} \times R \times {T(K)}}$

wherein R is the gas constant (8.3144621 L bar K⁻¹ mol⁻¹).

“Aquaporin” as used herein refers to selective water channel proteins,including AqpZ and SoPIP2;1 prepared according to the methods describedby Maria Karlsson et al. (FEBS Letters 537 (2003) 68-72) or as describedin Jensen et al. US 2012/0080377 A1.

“Asolectin” as used herein refers to a soybean lecithin fraction [IV-S]which is a highly purified phospholipid product containing lecithin,cephalin, inositol phosphatides & soybean oil (synonym: azolectin).

“Block copolymer” as used herein refers to membrane forming or vesicleforming di- and tri-block copolymers having both hydrophilic (A or C)and hydrophobic (B) blocks; the diblock copolymers being of the A-B orC-B type which are able to form bilayers and the triblock copolymersbeing of the A-B-A or A-B-C type that form monolayers by self assembly,where all of the membranes have the hydrophobic layer in the middle.Examples of useful diblock copolymers and examples of useful triblockcopolymers are disclosed in U.S. Pat. No. 5,364,633 and the following(all from the supplier Polymer Source):

Species Formula n_((hydrophobic)) n_((hydrophilic)) P7258 EO₄₈DMS₇₀ 7048 P5809 EO₁₅BO₁₆ 15 16 P8365 EO₂₅DMS₈ 8 25 P7259 EO₄₈DMS₁₄ 14 48 P7261EO₁₁₄DMS₁₄ 14 114 P3691B MOXA₆DMS₃₅MOXA₆ 35 12 P8061 MOXA₁₅DMS₆₇MOXA₁₅67 30 P9548 MOXA₁₅DMS₁₁₉MOXA₁₅ 119 30where EO-block-DMS-block represents poly(dimethylsiloxane-block-ethyleneoxide-block), EO-block-BO-block represents poly(butyleneoxide-block-ethylene oxide-block), and MOXA-block-DMS-block-MOXA-blockrepresentspoly(2-methyl-oxazoline-block-dimethylsiloxane-block-2-methyloxazoline).

“Thin-film-composite” or (TFC) membranes as used herein refers to a thinfilm membrane active layer having an additional aquaporin component,said layer being prepared using an amine reactant, preferably anaromatic amine, such as a diamine or triamine, e.g. 1,3-diaminobenzene(m-Phenylenediamine>99%, e.g. as purchased from Sigma-Aldrich) in anaqueous solution, and an acyl halide reactant, such as a di- or triacidchloride, preferably an aromatic acyl halide, e.g.benzene-1,3,5-tricarbonyl chloride (CAS No. 84270-84-8, trimesoylchloride (TMC), 98%, e.g. as purchased from Sigma-Aldrich) dissolved inan organic solvent where said reactants combine in an interfacialpolymerization reaction, cf. U.S. Pat. No. 4,277,344 which describes indetail the formation of a polyamide thin film formed at the surface of aporous membrane support, e.g. a polyethersulfone membrane. Morespecifically, benzene-1,3,5-tricarbonyl chloride can be dissolved in asolvent, such as a C6-C12 hydrocarbon including hexane (>99.9%, FisherChemicals), heptane, octane, nonane, decane etc. (straight chain orbranched hydrocarbons) or other low aromatic hydrocarbon solvent, e.g.Isopar™ G Fluid which is produced from petroleum-based raw materialstreated with hydrogen in the presence of a catalyst to produce a lowodor fluid the major components of which include isoalkanes. Isopar™ GFluid: Chemical Name: Hydrocarbons, C10-C12, isoalkanes, <2% aromatics;CAS No: 64742-48-9, chemical name: Naphtha (petroleum), hydrotreatedheavy (from ExxonMobil Chemical). Alternatives to the reactant1,3-diaminobenzene include diamines such as hexamethylenediamine etc.,and alternatives to the reactant benzene-1,3,5-tricarbonyl chlorideinclude a diacid chloride, adipoyl chloride etc. as known in the art. Tomake the active layer a thin film composite layer, an additionalcomponent, herein aquaporin water channels, that facilitates watertransport are added to the reactant solutions before interfacialpolymerization takes place. Said component may or may not participate inthe reaction, but preferably is inert to the reaction and becomesimmobilised in the thin film formed. Herein, the aquaporin waterchannels are preferably contained in vesicles, such as proteoliposomesand proteopolymersomes, formed from amphiphilic compounds.

“Proteoliposomes” as used herein are vesicles that typically have alipid to protein ratio (LPR calculated on a mole basis) of between 25 to500, such as about 100 to about 200.

“Proteopolymersomes” as used herein are vesicles that typically have apolymer to protein ratio (POPR calculated on a molar basis) of between25 to 500, such as about 50 to about 100 when using a triblock copolymerand a polymer to protein ratio of between 25 to 500, such as about 100to about 200 when using a diblock copolymer.

“Aquaporin membrane” as used herein refers to a membrane comprising anactive layer comprising immobilised aquaporin water channels and asupport layer. In said aquaporin membrane the aquaporin water channelsare immobilized or more or less embedded or partly embedded in or evensupported in or on said active layer. Said active layer is preferablycreated in close contact with a support layer, such as a typicalpolysulfone or polyether sulfone support membrane.

In one embodiment, the membrane comprises an active layer being a thinfilm composite (TFC) layer comprising aquaporin water channels.

Formation of a separation layer in the form of a thin film layer asknown in the art onto the surface of a support membrane (flat sheet orhollow fiber) results in changes to the water transport mechanism.Instead of water transport taking place by normal diffusion through thepores of the support membrane, another type of water transport takesplace through the thin film layer as is known from this type of reverseosmosis membranes, where membrane permeability is limited. The nonporousnature of the thin film separating layer results in transport of waterrequiring “jump diffusion” as described in Kotelyanskii et al. 1998.Thus, thin film modification of water membranes have mainly found use inreverse osmosis, where a hydrostatic pressure is required to force thewater through the membrane, and the obtained advantage lies in theimproved separation of unwanted solutes in the water to be filtered.These conventional membranes for reverse osmosis have effectively100-200 nm thick non-porous layers supported by a porous material. Waterpermeation in these membranes occurs as a diffusion process through thenon-porous layer established via the appearance and disappearance ofinterstitial spaces. The active layer used in the systems herein isfurther improved relative to the prior art thin film membranes by havingaquaporin water channels incorporated in the thin film layer making it athin film composite (TFC) layer. The incorporation of aquaporins havethe added benefit of providing a selective water transport through itspores having a diameter of only 2.4 Å at its narrowest passage (AqpZpore, cf. Wang et al. 2005) where an efficient single file watertransport takes place.

In a further embodiment the aquaporin water channels are incorporated invesicles before incorporation into the TFC layer. In a furtherembodiment the vesicles into which the aquaporin water channels areincorporated are liposomes or polymersomes. In a further embodimentliposomes are prepared from lipids such as DPhPC, DOPC, mixed soy beanlipids, asolectin or E. coli mixed lipids. In a further embodiment thepolymersomes comprise triblock copolymers of thehydrophile-hydrophobe-hydrophile (A-B-A or A-B-C) type or diblockcopolymers of the hydrophile-hydrophobe type (A-B).

Said aquaporin water channels are preferably AqpZ channels, but, inprinciple, all water selective aquaporins, e.g. such as aquaporin Z(AqpZ), Aqp1, G1pF or SoPIP2;1, are useful in the invention. In afurther embodiment the aquaporin water channels are AqpZ channels orSoPIP2;1 water channels.

In a further embodiment TFC layer is formed through interfacialpolymerization of an aqueous solution of a di- or triamine with asolution of di- or triacyl halide in an organic solvent, and wherein theaquaporin water channel vesicles are incorporated in said aqueoussolution.

The membrane may be manufactured at described by Zhao, Y. et al (2012).

“Flow cell” as used herein represents a filter (or membrane) module witha feed compartment and a non-feed compartment. The flow cell may beadapted for RO, e.g. having a feed solution inlet and a permeate outlet,or the flow cell may be adapted for FO where an inlet and an outlet forfeed solution is fitted on one side of the cell to allow fluidcommunication with the membrane, and an inlet and an outlet for drawsolution is fitted on the opposite side of the cell to allow fluidcommunication with the opposite side of the membrane. Examples of usefulflow cells include the following from Sterlitech Corp, WA, US.(http://www.sterlitech.com):

FO cell: CF042-FO (Delrin Acetal or Acrylic)

RO cell: CF042 Crossflow Cell

Membranes of size 5.5 cm×11 cm fit into the CF042 cells.

FO/RO cell: SEPA CF II

This cell can have an RO top or an FO top. Membranes of size 13.5 cm×19cm fit into the SEPA CF II cell.

“Impaired ground water” is used herein synonymously with the terms“contaminated ground water” and “polluted ground water”, all of whichterms are well known to the person skilled in the art.

Cleaning of the Membrane in the Systems

Membrane fouling can cause flux decline and affect the quality of thewater extraction process. The degree of fouling may be controlled suchas by measuring flux decline as determined by flow rates of feed anddraw solutions at specific points in the water extraction system. Thesystems for water extraction may also include means for maintenancepurposes, such as means for introducing air or a cleaning solution orsuch as for the utilisation of physical and/or chemical cleaningtechniques. Physical methods for cleaning the membrane of the waterextraction system include forward and reverse flushing, backwashing, airflushing (also called air scouring) and sponge ball cleaning (Al-Amoudi2007). In one embodiment, the water extraction system may be cleaned byintroducing bubbles into the cleaning solution for air scouring.

With respect of chemical cleaning, Al-Amoudi et al. (2007) gives anoverview of cleaning systems for nanofiltration membranes and Porcelliet al. (2010) gives a review of chemical cleaning of potable watermembranes. One example of cleaning reagent is citric acid that canprovide buffering and has chelating abilities. Further citric acid candisrupt biofilm formation by removing minerals from foulant layers. Asecond example of cleaning reagent is EDTA (ethylenediamine tetraaceticacid) which provides chelation capacity for metals such as calcium anddispersed minerals in general.

Robust Operation Conditions

The water extraction system of the invention is useful under varied pHand temperature conditions due to the robustness of the aquaporinmembrane, which can tolerate pH values as low as 2 and as high as 11 andtemperatures as high as 65° C. and as low as 10° C. The water fluxbecomes reversibly reduced during very high and very low pH andtemperature feed values, so that the membrane regains its high initialperformance, cf. the tables below:

Results for FO experiments using TFC-AqpZ membrane in a CF042 cell athigh and low feed pH:

Amphiphile n J_(w) (L/m²h) J_(s) (g/m²h) J_(s)/J_(w) R_(Ca) (%) P8061 -pH 6.3 14 12.60 ± 1.21 3.88 ± 0.83 0.31 99.80 ± 0.22 P8061 - pH 2.0 3 5.60 ± 0.79 — — P8061 re-run 3 12.22 ± 0.95 4.32 ± 0.26 0.35 99.71 ±0.19 pH 6.3 P8061 - pH 11.0 3  7.44 ± 0.57 — — P8061 re-run 3 11.49 ±2.42 4.17 ± 0.49 0.36 99.55 ± 0.16 pH 6.3

The results in the table above clearly shows that the FO system is pHsensitive and pH tolerant and that the membrane performance as measuredby water flux (J_(w)), reverse salt flux (J_(s)) and calcein rejection(R_(Ca)) is reversible at neutral pH. The calculated J_(s)/J_(w) valuesare based on the average values and generally shows a consistentmembrane performance at all pH values tested. Thus, it is a furtherpurpose of the invention to provide a water extraction system having astable performance in the pH range of from about pH 2 to about pH 11 asdefined by the J_(s)/J_(w) values. In a special aspect the inventionprovides a water extraction system for use in a low pH process, such asa low pH forward osmosis process, such as a process at a pH below 6, 5,4 or 3. In a further special aspect the invention provides a waterextraction system for use in a high pH process, such as a high pHforward osmosis process, such as a process at a pH above 8, 9, 10 or 11.

In addition, the water extraction system of the invention is heattolerant. However, it was found that operation at both 10° C. and 65° C.has an impact FO performance. At 65° C. high water fluxes areaccompanied by higher reverse salt flux values. Operation at 10° C.results in a lower water flux and a high retention. Operation at 50° C.obtains water fluxes and salt rejection values that are comparable tothe performance standards of the reference system at 22° C. for aTFC-aquaporin membrane using P8061 as amphiphilic vesicle formingmaterial (amphiphile) and in a system where the feed solution containsdissolved calcein as a trace material. Finally, it was found thatmembrane exposure to 10° C. and 65° C. for about 1200 minutes does notcause any damage to the membrane and that successive standard FOoperation of the system was not negatively influenced. Results are givenin the table below:

Results for FO experiments using TFC-AqpZ membrane in a CF042 cell athigh and low feed temperatures:

Amphiphile n J_(w) (L/m²h) J_(s) (g/m²h) J_(s)/J_(w) R_(Ca) (%) P8061 1412.60 ± 1.21 3.88 ± 0.83 0.31 99.80 ± 0.22 Reference - 22° C. P8061 -65° C. 3 22.09 ± 3.93 7.49 ± 3.4  0.33 99.75 ± 0.29 P8061 Re-run - 111.55 4.08 0.35 99.81 22° C. P8061 - 50° C. 3 20.16 ± 6.20 3.67 ± 2.410.18 99.92 ± 0.06 P8061 Re-run - 1 12.37 2.43 0.36 99.70 22° C. P8061 -10° C. 3  7.02 ± 0.16 2.43 ± 0.89 0.34 99.95 ± 0.02 P8061 Re-run - 113.16 3.30 0.25 99.95 22° C.

The results in the table above clearly shows that the FO system is heatsensitive and heat tolerant and that the membrane performance asmeasured by water flux (J_(w)), reverse salt flux (J_(s)) and calceinrejection (R_(Ca)) is reversible at room temperature. In addition, thecalculated J_(s)/J_(w) values based on the average values in the abovetable show that the membrane performance is unaffected by changes intemperature in the interval from 10 to 65° C. Thus, it is a furtherpurpose of the invention to provide a water extraction system having astable performance in said temperature interval as defined by theJ_(s)/J_(w) values. In a special aspect the invention provides a waterextraction system for use in a high temperature process, such as a hightemperature forward osmosis process, such as a forward osmosis processat a temperature above 30, 40, 50 or 60° C.

The present invention is further illustrated by the following examples,which should not be construed as limiting the scope of the invention.

EXPERIMENTAL SECTION Preparation of Vesicles (Liquid Membrane)

Preparation of 1 mg/mL Asolectin proteoliposomes, and lipid to proteinratio (LPR) 200 using AqpZ Mw 27233 according to the following protocol:

1. Fill a 50 mL glass evaporation vial with 5 mL of a 2 mg/mL stocksolution of asolectin (mW 786.11 g/mol, Sigma) in CHCl₃.

2. Evaporate the CHCl₃ using a rotation evaporator for at least 2 h tocomplete dryness.

3. Add 0.8 mL of buffer solution (1.3% octylglucoside (OG) in PBS pH7.4) to rehydrate the film obtained in the evaporation vial in step 2.

4. Shake the vial at maximum rpm on a platform shaker (Heidolph orbitalplatform shaker Unimax 2010 or equivalent) until the lipid is dissolved.

5. Add 1.73 mg of AqpZ in a protein buffer containing Tris pH8, glucoseand OG, 10 mg/mL, and rotate vial for 15 min at 200 rpm, the AqpZ beingprepared according to description above.

6. Slowly add 9.03 ml PBS (pH 7.4 without OG), and shake vial for 15 minat 200 rpm.

7. Freeze/thaw the combined solution/suspension on dry ice/40° C. waterbath for three times to eliminate possible multilamellar structures.

8. Add 250 mg of hydrated Biobeads (SM2 from BioRad) and rotate vial for1 h at 200 rpm at 4° C. to adsorb detergent (OG).

9. Add further 250 mg of hydrated Biobeads and rotate vial for 2 to 3days at 200 rpm at 4° C.

10. The Biobeads with adsorbed OG are then removed by pipetting off thesuspension.

11. Extrude the obtained suspension for about 11 times through a 200 nmpolycarbonate filter using an extruder, such as from at least 1 time andup to about 22 times to obtain a uniform proteoliposome suspension inthe form of a vesicles (a liquid membrane) suspension.

Instead of using BioBeads, the detergent can be removed on a typicalresin column, such as an Amberlite XAD-2.

Protocol for 1 mg/ml proteo-polymersomes, protein to polymer ratio(POPR) 50 Polyoxazoline Based Triblock Copolymers, Poly(2-methyloxazoline-b-dimethyl siloxane-b-2-methyl oxazoline), Moxa 30: DMS 67, Mw7319 (P8061 purchased from Polymer Source™, Quebec, Canada), AqpZ Mw27233

1. Fill a 50 ml glass evaporation vial with 5 ml of a 2 mg/ml stocksolution of P8061 in CHCl3.

2. Evaporate the CHCl3 using a rotation evaporator for at least 2 h tocomplete dryness.

3. Add 3.0 mL of buffer solution (1.3% O.G.; 200 mM Sucrose; 10 mM TrispH 8; 50 mM NaCl) to rehydrate the film obtained in the evaporation vialin step 2.

4. Shake the vial at 200 rpm on a platform shaker (Heidolph orbitalplatform shaker Unimax 2010 or equivalent) for 3 hours to obtaindissolution of the copolymer.

5. Add 75 μL of AqpZ in a protein buffer containing Tris, glucose andOG, and rotate vial over night at 200 rpm and 4° C.

6. Add 6.88 ml buffer (10 mM Tris pH 8; 50 mM NaCl) slowly while mixingup and down with pipette.

7. Add 180 mg hydrated Biobeads and rotate for 1 h at 200 rpm.

8. Add 210 mg hydrated Biobeads and rotate for 1 h at 200 rpm.

9. Add 240 mg hydrated Biobeads and rotate O.N. at 200 rpm 4° C.

10. Add 240 mg hydrated Biobeads and rotate O.N. at 200 rpm 4° C.

11. The Biobeads with adsorbed OG are then removed by pipetting off thesuspension.

12. Extrude the suspension for about 21 times through a 200 nmpolycarbonate filter using an extruder, such as from at least 1 time andup to about 22 times to obtain a uniform proteopolymersome suspension(vesicles) suspension.

TFC Active Layer Preparation: Materials:

Apolar solvent: Hexane or an isoparaffin solvent, such as Isopar G,ExxonMobil Chemical

TMC: 1,2,5 Benzenetricarbonyltrichloride from Aldrich 147532

MPD: m-Phenyldiamine from Aldrich P23954

Vesicles: Proteopolymersomes or proteoliposomes prepared as describedabove, e.g. using p8061-MOXZDMSMOXZ(Poly(2-methyloxazoline-b-dimethylsiloxane-b-2-methyloxazoline) fromPolymer Source Inc., Quebec, Canada, with AQPZ (POPR 50) Supportmembrane: MICROPES 1FPH or 2FPH manufactured by Membrana GmbH.

Interfacial Polymerization:

Interfacial polymerization is a polymerization reaction that is takingplace at the interface between two immiscible liquids with differentmonomers dissolved. Here, MPD is dissolved in water and vesicles areadded. The porous PES support membrane, e.g. a MICROPES 1FPH or 2FPHmembrane from Membrana GmbH is cut in rectangular shape, e.g. 5.5 cm×11cm, 13.5 cm×19 cm, or 20 cm×25 cm, and soaked in the aqueous solutionand the surface is dried just enough to have a dry surface with aqueoussolution filled pores. TMC is dissolved in an apolar solvent (hexane orIsopar™) and applied to the surface of the semidried soaked supportmembrane. The MPD and TMC react at the interface between the two liquidsand form a highly cross-linked network of aromatic polyamide. TMC reactswith water to give a carboxylic acid group and HCl, thus the TMC isbroken down in the aqueous phase. MPD reacts readily with TMC, thus itdoes not diffuse far into the apolar solvent. The resulting layer is ahighly cross-linked aromatic polyamide film embedded in the supportmembrane surface with a thickness of approximately 100-700 nm. Thevesicles become immobilized by being trapped or embedded in thecross-linked polyamide film.

Example 1 System for Removal of Boron Contamination in a FreshwaterSource Using FO and RO

FIG. 4 shows a system for water extraction with boron removal using aWashguard SST pump (16) and an osmotic cell (Sterlitech CF042) for ROfiltration, where said cell holds a 5.7 cm×11.3 cm TFC-AqpZ membraneprepared as described herein, and wherein a boron contaminated freshwater feed source created by dissolving boric acid to about 5 mg/L B intap water having a mean content of 187 μg/L B, 0.20 μg/L As, 113 mg/LCa, pH=7.5 (source: HOFOR, Copenhagen 2011) is filtered through saidmembrane during RO operation mode at a pressure of 125 psi. Theresulting permeate can be sampled for ICP-MS boron elemental analysis,e.g. according to Nagaishi & Ishikawa (2009), giving a calculatedrejection range based on the obtained analytical data of from about 45%to about 55% rejection comparable to the results obtained by Kim et al.2012.

FIG. 2 shows a system for water extraction with boron removal using thesame feed source as in the RO experiment above and a draw solution of 35g/L NaCl in tapwater (same tap water source as for the feed) in a closedcircuit. The FO system uses a Sterlitech CF042P osmotic cell adapted forFO mode, where said cell holds a TFC-AqpZ membrane prepared as describedherein, cf. the figure. The FO system is operated with counter-currentflow velocities of 50.03 ml/min corresponding to 0.85 cm/s, and bothactive side of membrane against draw and active side of membrane againstfeed solutions were tested. After 1300 min operation samples for ICP-MSboron elemental analysis were taken from the draw solutions giving acalculated rejection range based on the obtained analytical data of fromabout 60% to about 85% representing potential for improved rejectionduring FO compared to the results published by Kim et al. 2012.

Tabulated results from 10 FO experiments with membranes having an activearea of 8.5 cm×3.9 cm prepared as described above and a feed solutioncomprising 5 mg/mL of boron in the form of boric acid in tapwateradjusted vs. 2M NaCl draw solution:

Active membrane layer on the non-feed side (against draw solution) cf.FIG. 1C

Date & Jw/LMH Js/GMH B Rejection at app. configuration 900 min 900 min1300 min 220812 AL-DS 11.83 1.99 62% 300812 AL-DS 11.39 2.02 65% 091012AL-DS 9.1 1.64 74% 101012 AL-DS 9.31 1.09 76% 221012 AL-DS 10.54 5.6653% Mean Value 10.43 2.48 66% Std. 10% 66% 13%

Active membrane layer on the feed side (against feed solution) cf. FIG.1C

Date & Jw/LMH Js/GMH B Rejection at app. configuration 900 min 900 min1300 min 220812 AL-FS 12.07 3.41 64% 091012 AL-FS 6.8 1.68 82% 101012AL-FS 8.24 1.15 86% 221012 AL-FS 9.19 1.75 77% Mean Value 9.08 1.997577% Std. 21% 42% 11%

In these experiments the FIG. 1B membrane configuration showed a higherrejection % and is thus advantageous.

In addition, 5 reverse osmosis experiments with active membrane layer onthe side of a feed solution of 5 mg/ml Boron as boric acid in tapwater,flow 0.25 m/s and applied pressure of 8.62 bar showed a mean value ofboron rejection of 50%±8%.

Example 2 System for Removal of Arsenic Contamination in a FreshwaterSource Using FO and RO

The same RO system as described in Example 1 was used except that anartificially created feed solution of 5 mg/L As (arsenic acid dissolvedin MilliQ water and adjusted to pH 9.5 using 1N NaOH) is filteredthrough said membrane during RO operation mode at a pressure of 125 psi.The resulting permeate can be sampled for ICP-MS arsenic elementalanalysis, e.g. as described by Grosser (2010), giving a calculatedrejection range based on the obtained analytical data of about 100%rejection.

The same FO system as described in Example 1 was used except that a feedsolution of 5 mg/L As in MilliQ water, pH 9.5, and a draw solution of 2MNaCl in MilliQ water was used. After 1300 min operation samples forarsenic elemental analysis were taken from the draw solutions for ICP-MSanalysis. The results show that a calculated arsenic rejection based onthe obtained analytical data of about 100% can be obtained using FOfiltration (both when using the active side of the TFC membrane againstthe draw solution and using the active side of the TFC membrane againstthe feed solution).

Tabulated results from 10 FO experiments with membranes having an activearea of 8.5 cm×3.9 cm prepared as described above and a feed solutioncomprising 5 mg/L of arsenic in the form of As₂O₃ in milliQ wateradjusted to pH 9.5 vs. 2M NaCl draw solution:

Active membrane side against non-feed (draw), cf. FIG. 1C

Date & Jw/LMH Js/GMH As Rejection at app. configuration 900 min 900 min1300 min 240812 AL-DS 11.5 4.69 103% 161012 AL-DS 15.37 4.81 113% 171012AL-DS 15.01 7.61 98% 241012 AL-DS 14.97 8.91 102% 251012 AL-DS 13.014.94 94% Mean Value 13.97 6.192 102% Std. 11% 28% 6%

Active membrane layer against feed, cf. FIG. 1B

Date & Jw/LMH Js/GMH As Rejection ca configuration 900 min 900 min 1300min 240812 AL-FS 10.81 5.81 102% 161012 AL-FS 11.3 2.67 102% 171012AL-FS 14.28 4.01 102% 241012 AL-FS 11.6 1.67 105% 251012 AL-FS 11.6 2.3195% Mean Value 11.92 3.294 101% Std. 10% 45% 3%

In addition, 5 reverse osmosis experiments were run where the activeside of the same type of membrane was positioned against the feedsolution comprising 5 mg/L of arsen in the form of As₂O₃ in milliQ wateradjusted to pH 9.5, flow 0.25 m/s and applied pressure of 8.62 bar.These experiments consistently showed a mean value of arsenic rejectionof 98%±1%.

Example 3 System Comprising an FO Concentrator Module, e.g. for PeptidesMethod:

FO module is prepared by the following steps:

-   -   1. water tight fastening, such as gluing with silicone glue or        otherwise clamped tight, of a plastic measuring cylinder (such        as having a diameter of 1 cm and the like depending on volume to        be up-concentrated) to a Plexiglas surface with a corresponding        hole of area 0.5 cm2 or 3.14 cm2, where the feed solution will        be exposed to the membrane.    -   2. A mesh support is glued immediately underneath.    -   3. A TFC-AqpZ membrane, such as prepared using 1 FPH support        membrane and

P8061 amphiphilic copolymer for the polymersomes, was prepared asdescribed above, where active side on top is glued under the support or,alternatively, water tight fastened with O-ring.

-   -   4. Optionally, a rubber gasket may be glued after the membrane.    -   5. An additional rubber gasket can be added as a cushion when        the top part is assembled with the bottom part where the tubing        is placed, cf. FIG. 7 or 8 below.    -   6. The module is now connected to a pump, such as a peristaltic        pump where draw solution is recirculated through the system,        typically at flow speed of 40 mL/min. An osmotic gradient        created by using 2M NaCl in MilliQ water as draw solution drives        the movement of water from the feed solution in the measuring        cylinder to the draw.

Detection of Feed Solute (Peptide or Protein or Other Sample):

In this example a concentrated feed solution of the custom made peptideGGGSGAGKT (available from Caslo Laboratory as a lyophilizedtrifluoroacetate salt, molecular weight measured by MS of 690.71, purity98.87%) or of the amino acid L-lysine (from Sigma Aldrich, molecularweight 146.1 g/mol, 97% purity)) was mixed with equal volumes of LavaPepkit (from gelcompany.com, the kit binds to lysine residues in peptidesand is used herein experimentally also to detect the free amino acid)and incubated for 1 h in the dark at room temperature. Detection ofpeptides and L-lysine is done on QuBit with the setting “ssDNA”.Detection range of ssDNA on QuBit: excitation: 400-490 nm, 500-645 nm;emission: 570-645 nm.

Generation of Standard Curve:

Peptide/lysine in 6 different concentrations ranging from 1000 to 1μg/mL in 9.3×TES buffer is analysed, the concentrations being suitabledue to feed getting concentrated about 2 to 6 times during theup-concentration.

Quantification: 10 μL of concentrated solution (2 to 5× conc.)+90 μL10×TES buffer to end up at 9.3× buffer in the dilution+100 μL kit.

Detection range of LavaPep kit: excitation: 405-500 nm (green 543, 532nm, blue 488 nm, violet 405 nm or UVA); emission: max 610 nm (band passor 560 long pass)

Excitation: 540+−10 nm; emission: 630+−10 nm

The concentrated feed solution of the peptide/lysine is detected andmeasured as follows:

1. Start feed: about 50 μg/mL peptide or lysine in 1×TES buffer

2. Run assay

3. Collect concentrated solution

4. 10 μg/mL conc. peptide sol.+90 μg/mL 10×TES buffer+100 μg/mL kit

5. Incubation in the dark for 1 h at room temperature

6. Measure fluorescence counts in QuBit

7. Read concentration from standard curve

Solutions:

Feed: 200 μg/mL L-lysine (amino acid example), or 50 μg/mL-500 μg/mL ofpeptide in 1×TES buffer, or 500 μg/mL of bovine serum albumin (BSA) usedas a protein example in PBS buffer (0.303 Osm)

Draw solution: 2M NaCl (200 mL) in MilliQ water

Peptide, protein and L-lysine kit: LavaPep kit (fluorescent compound:epicocconone, binds to lysine, and is used for quantification of lysineresidue in peptide). Preferably, Lysine (and other amino acids) may bequantified using HPLC.

Results for the up-concentrations are as follows

Experimental conditions: A large scale experiment using 1 L of feed and1 L of draw solutions in the Sterlitech CF042 chambers

Feed: 200 μg/mL L-lysine in 1×TES buffer

Draw: 2M NaCl

Operation time: about 1175 min

End concentration L-lysine is concentrated about 7 times

Experimental conditions: A large scale experiment as above

Feed: 200 μg/mL L-lysine in 1×TES buffer

Draw: 2M NaCl

Operation time: about 1175 min

End concentration L-lysine is concentrated about 6 times

Experimental conditions: small scale, 1 mL

Feed: 50, 200 or 500 μg/mL GGGSGAGKT in 1×TES buffer

Draw: 2M NaCl

Operation time: about 1175 min

The upconcentration of the volumes and peptide concentrations are in thetable below:

Concentration Volumen Peptide of feed, upconcentration upconcentrationstart [μg/mL] [times] [times] 50 2.3 1.9 200 5 6 500 4.3 4.8

Conclusion: the results clearly show that during less than 20 hours offorward osmosis operation in the system the feed L-lysine solutes can beconcentrated up to about 6 to 7 times, and for the feed peptidesolutions these can be concentrated up to 6 times with the feed volumebeing concentrated in the same order of magnitude.

Example 4 Treatment of the Membrane with Citric Acid

Membranes were prepared as described in the experimental section aboveand were tested for robustness against treatment with citric acid. Themembranes were submerged in a 0.3% citric acid solution and left soakingfor 15 minutes (n=3).

Before and after the soaking process the membranes were run in FO mode(with 5 μM calcein feed and 2 M NaCl as draw solution) in a CF042 flowcell for 900 min.

The results of the tests are in the table below:

J_(w) [L/m²h] J_(s, total) [g/m²h] R_(calcein) [%] Before treatment10.33 2.26 99.94 (n = 3) After treatment 11.43 3.40 99.76 (n = 3)

wherein J_(w) is the water flux through the membrane,

J_(s, total) is the reverse salt flux through the membrane and

R_(calcein) is the calcein rejection.

As can be seen from the table, the treatment does not influence thewater flux negatively and the calcein rejection is maintained at a veryhigh level.

Example 5 Treatment of the Membrane with EDTA

Membranes were prepared as described in the experimental section aboveand were tested for robustness against treatment with EDTA. Themembranes were submerged in a 0.8% EDTA solution and left soaking for 15minutes (n=3).

Before and after the soaking process the membranes were run in FO mode(with 5 μM calcein feed and 2 M NaCl as draw solution) in a CF042 flowcell for 900 min.

The results of the tests are in the table below:

J_(w) [L/m²h] J_(s, total) [g/m²h] R_(calcein) [%] Before treatment (n =3) 10.06 2.23 99.94 After treatment (n = 3) 10.99 3.51 99.00

wherein J_(w) is the water flux through the membrane,

J_(s, total) is the reverse salt flux through the membrane and

R_(calcein) is the calcein rejection.

As can be seen from the table, the treatment does not influence thewater flux negatively and the calcein rejection is maintained at a veryhigh level indicating an intact membrane.

Example 6 Water Extraction System for FDFO

In this example the principle of Fertilizer Drawn Forward Osmosis (FDFO)was tested in a forward osmosis water extraction system according to thepresent invention with the objective of studying rejection rates oftypical plant nutrient salts contained in fertilizer and achievablewater flux values.

Protocol:

A concentrated nutrient solution of 66.62 g/L was prepared by dissolvingin water e.g. tap water or MilliQwater, a dry NPK granulate from DanishAgro having the following composition: total N 14.0%, nitrate-N 5.7%,ammonium-N 8.3%, phosphorus (citrate and water soluble) 3.0%, Potassium(water soluble) 15.0%, Magnesium total 2.5%, sulfur total 10.0% andboron total 0.02%.

The resulting solution can be used as the draw source in a combinedFDFO/desalination system, cf. FIG. 3. Alternatively, a commercialconcentrated liquid plant nutrient solution, Blomin (The Scotts Company(Nordic), Glostrup DK) can be used. This nutrient solution consists offollowing nutrient salt composition and concentration: nitrogen(N)—4.4%; Phosphorus (P)—0.9%; potassium (K)—3.3%; Boron (B)—0.0002%;copper (Cu)—0.006%; iron (Fe)—0.02%; Manganese (Mn) —0.008%, Sulfur(S)—0.0003%; Molybdenium (Mo)—0.0002%; and Zinc (Zn) —0.004%.

With reference to FIG. 3 the system comprises a seawater feed source(10), the water being sampled from Øresund close to the coast at TuborgHarbour, Copenhagen, said water having an approximate salinity of about8.7 g/L; (13) is a contained with the concentrated fertilizer solutionprepared as described above (optionally fitted with a magnetic stirreror the like); (1) is a Sterlitech CF042 flow cell with a TFC-AqpZmembrane (active area 0.003315 m2) prepared as described in theexperimental section above using P8061 copolymer; (12) is a containerwith the partly diluted fertilizer solution which can be re-circulatedto achieve higher degree of dilution; (14) is the additional freshwatertank (normal tap water can be used) for final adjustment of the degreeof dilution of the fertilizer solution; (11) is the concentrated feedstream, e.g. up-concentrated seawater; (15) is the diluted fertilizersolution ready for use. The system will initially run for about 900 minand is expected to result in a sufficiently diluted plant nutrientsolution ready for use or ready for use after further dilution, cf. FIG.3 and explanations to FIG. 3 herein.

Example 7 A Water Extraction System with Separation of Urea from ROPermeate in Dairy Industries

With reference to FIG. 4 the system comprises a feed tank (18) withdairy process water having between 45 to 75 mg/L total N correspondingto about 110 mg/L urea; (16) is a pump; (17) is a valve; (19) is thepermeate and (20) is the permeate tank. The flow from the pump(Washguard SST) through the Sterlitech CF042 flow cell and back to thevalve is a pressurized flow of 125 psi and cross flow speed 0.26 m/s;the remaining flows are not pressurized flows. The permeate content ofurea is expected to be reduced by at least 50%.

With reference to FIG. 5 the system comprises a feed stream (21) havingthe same composition as above in (18); (1) is the Sterlitech CF042P flowcell with the aquaporin membrane (2) prepared as described in theexperimental section above; (22) is the concentrated feed stream; (23)is the concentrated draw solution; (8) the draw solution, e.g. 35 g/LNaCl in tapwater corresponding to typical Kattegat salinity, in fluidcommunication with the flow cell; (24) the diluted draw solution; (9)the draw solution recovery system; and (25) the desalinated productwater free of draw solution solutes. Both feed and draw streams arepumped through the flow cell in counter-current mode at a flow speed of50.03 ml/min. The resulting urea rejection in this system is expected tobe about 75%.

Example 8 A Water Extraction System for Storage of Renewable Energy

This example shows the use of the water extraction system for storingenergy from renewable sources, such as energy from sunlight, wind,tides, waves and geothermal heat (i.e. green energy). These energysources are often intermittent in their nature and there is a highdemand for systems for storing such energy.

The storage of energy as a salt gradient as described in this example iscomparable with the commonly used process, wherein water is pumped to ahigher level location, such as mountains during excess of electricalenergy. When the demand of electrical energy is higher than theproduction capacity, the potential energy of the water is used to drivea turbine. Whereas this known technology is easy to apply in mountainregions it cannot be applied in low level areas or off shore.

With the system according to this Example, energy generated by (offshore) windmills, wave power, solar cells or any other renewable energysource can be stores as salt gradients.

With the reference to FIG. 11, if the renewable energy source producesmore electrical power than the grid can take up, the energy can be usedto concentrate an aqueous solution, such as seawater or even waste waterby the process of reverse osmosis. All that is needed is a reservoir forsalt solution (64) (which in its simplest form could be the ocean), areservoir for the desalted water (63), a pressure delivering pump (16)run by the surplus electrical power, and a flow cell (1) with theosmosis membrane (2). The pressure gradient forces the freshwater(desalted seawater) to be pressed through the membrane, leaving behindconcentrated saltwater.

At times, where more electrical power is needed than the renewableenergy source can generate, the process can be reversed by use ofpressure retarded osmosis (PRO). In this process, the salt gradientbetween the salt solution side (61) and the desalted water side (62)generates a hydraulic pressure over the osmosis membrane. Since the saltcannot pass through the membrane but the water, the water will pass themembrane towards the higher salinity (higher salt concentration) andthereby create hydraulic pressure, which then can be turned intoelectrical power through the generator (31). Depending on the salinityof the depressurized diluted salt solution, the stream can either goback (via 66) to the salt solution tank (64) or be let out of thesystem. An inlet (67) can supply the system with a fresh supply of saltsolution.

Example 9 A Water Extraction System for Re-Extraction of HemodialysisWater from Used Dialysis Solution

This example shows the use of the water extraction system of theinvention for post treatment of dialysate solution, cf. FIG. 1. Thedialysate solution is a diluted aqueous solution of mineral ions andglucose, which typically runs in a counter-current flow with blood froma patient through a hollow fiber ultrafiltration module duringhemodialysis. Sam et al. (2006) discloses composition and clinical useof hemodialysates. The dialysate solution will maintain a sufficientconcentration gradient across an ultrafiltration membrane with respectto the solutes that have to be removed from the blood, such as urea,degradation products such as indoxyl sulphate and p-cresol, and excesspotassium and phosphorous, and thus maintain efficiency of the dialysis.For this purpose large quantities of ultrapure water is needed, i.a.about 400 L of water per week. The water extraction systems describedherein are useful in systems for reuse of this ultrapure water, such asin a closed loop where the (diluted) used dialysate solution, afterbeing used in hemodialysis, e.g. after absorbing waste materials such asurea from blood by passing through a hemodialysis filter may function asthe source solution (7) when passing through a further membrane module,i.e. the flow cell (1) containing an aquaporin membrane, and where aconcentrated fresh dialysate solution (dialysis fluid) may function asthe draw solution. Ideally, the concentrated dialysate can besufficiently diluted so as to be directly used for continuedhemodialysis. This could be achieved by applying a slight pressure onthe feed side of the aquaporin containing membrane (using the concept ofassisted forward osmosis). In this way only pure water is extracted fromthe contaminated, used dialysate solution and this extracted pure wateris used as a replacement for the otherwise required new supplements ofultrapure water for dilution of the dialysate concentrate.

An additional advantage would result from the used dialysate solutionbecoming concentrated resulting in a smaller volume for waste disposal.

REFERENCES

-   Zhao, Y et al, Synthesis of robust and high-performance    aquaporin-based biomimetic membranes by interfacial    polymerization-membrane preparation and RO performance    characterization, Journal of Membrane Science, Volumes 423-424, 15    Dec. 2012, Pages 422-428.-   Kim et al. Journal of Membrane Science 419-420 (2012) 42-48.-   Branislav Petrusevski, Saroj Sharma, Jan C. Schippers (UNESCO-IHE),    and Kathleen Shordt (IRC), Reviewed by: Christine van Wijk (IRC).    Arsenic in Drinking Water March 2007, IRC International Water and    Sanitation Centre-   Nagaishi & Ishikawa (Geochemical Journal, Vol. 43, pp. 133 to 141,    2009)-   Grosser, Z., Oct. 13, 2010 (downloaded from internet on 20130219):    <url:    http://www.watertechonline.com/articles/the-challenge-measure-arsenic-in-drinking-water>-   Hill & Taylor, 15 Jul.-19 Jul. 2012, Use of Aquaporins to Achieve    Needed Water Purity on the International Space Station for the    Extravehicular Mobility Unit Space Suit System. In: (ICES) 42^(nd)    International Conference on Environmental systems, San Diego, Calif.-   Al-Amoudi et al, Journal of Membrane Science 303 (2007) 4-28.-   Porcelli et al, Separation and Purification Technology 71 (2010)    137-143-   Achilli et al. Selection of inorganic-based draw solutions for    forward osmosis applications. Journal of Membrane Science 364 (2010)    233-241-   Phuntsho et al. A novel low energy fertilizer driven forward osmosis    desalination for direct fertigation: Evaluating the performance of    fertilizer draw solutions. Journal of Membrane Science 375 (2011)    172-181.-   Sam et al. Composition and clinical use of hemodialysates.    Hemodialysis International 2006; 10: 15-28

1. A water extraction system comprising: a) a flow cell (1) comprising amembrane (2); said membrane comprising an active layer (3) comprisingimmobilized aquaporin water channels and a support layer (4), and saidmembrane having a feed side (5) and a non-feed side (6); and b) anaqueous source solution (7) in fluid communication with the feed side ofthe membrane.
 2. The water extraction system according to claim 1wherein said active layer is a cross linked aromatic amide thin film,wherein aquaporin vesicles are incorporated, said vesicles being formedby self assembly of amphiphilic lipids or block copolymers in thepresence of an aquaporin protein suspension.
 3. The water extractionsystem according to claim 1 or 2 wherein said active layer is a crosslinked aromatic amide layer, preferably formed by interfacialpolymerization, and said vesicles are formed from an amphiphilic lipidor triblock copolymer solution, such as asolectin or aPMOXAa-PDMSb-PMOXAc copolymer,
 4. The water extraction system accordingto any one of claims 1 to 3 wherein said aquaporin is selected from aplant aquaporin, e.g. SoPIP2;1; a mammal aquaporin, e.g. Aqp1; and abacterial aquaporin, e.g. aquaporin-Z.
 5. The water extraction systemaccording to any one of claims 1 to 4 wherein said support layer is apolysulfone or polyether sulfone support membrane.
 6. The waterextraction system according to any one of claims 1 to 5 for use in ahigh temperature process.
 7. The water extraction system according toany one of claims 1 to 5 for use in a high pH process.
 8. The waterextraction system according to any one of claims 1 to 5 for use in a lowpH process.
 9. The water extraction system according to any one ofclaims 1 to 8 for forward osmosis (FO) wherein the non-feed side of themembrane functions as draw side; and said system further comprising: c)an aqueous draw solution (8) in fluid communication with the draw sideof the membrane, and, optionally d) further comprising a draw solutionconcentration unit (9).
 10. The water extraction system according to anyone of claims 1 to 9 further comprising means for regeneration oranti-fouling of said membrane, said means comprising a cleaning fluidhaving a pH of about 2 to 11, said cleaning fluid being selected from asolution of an organic acid, such as citric acid, or a chelating agent,such as EDTA.
 11. The water extraction system according to any one ofclaims 1 to 10 for use in a fertigation system.
 12. A fertigation systemcomprising the following features with (reference to FIG. 3): i) a feedstream (10), ii) a pump (16), iii) a flow cell (1), preferably a crossflow cell, with an aquaporin membrane, preferably a TFC-aquaporinmembrane (2), iv) a concentrated plant nutrient draw solution (13), v) adiluted draw solution (12) in fluid communication with the draw side ofthe membrane (8), vi) an optional fresh water source (14) for additionaldilution of diluted draw, and vii) a resulting diluted plant nutrientsolution ready for use (15); and wherein said diluted draw solution maybe recirculated through the flow cell to achieve higher degree ofdilution.
 13. The water extraction system according to any one of claims1 to 10 for use in up-concentration of organic solutes, such as aminoacids, peptides, and proteins.
 14. The water extraction system accordingto claim 13 substantially as shown in FIGS. 7 to
 10. 15. A waterextraction system according to any one of claims 1 to 8 for reverseosmosis, wherein the non-feed side of the membrane functions as thepermeate side; and said water extraction system further comprising: e) apermeate in fluid communication with the permeate side of the membrane.16. The water extraction system according to claim 15 where said sourcesolution is pumped through said flow cell at a cross flow speed of about0.10 m/s to about 0.30 m/s, such as about 0.26 m/s, and at a pressure ofabout 100 psi to about 130 psi, such as about 125 psi.
 17. A reverseosmosis system according to claims 15 and 16 comprising the followingfeatures (with reference to FIG. 4): i) a feed solution tank (18), ii) apump (16), iii) a valve (17), iv) a flow cell adapted for reverseosmosis (1), v) a TFC-aquaporin membrane (2) vi) a permeate compartment(19), and vii) a permeate stream, optionally being collected in apermeate tank (20)
 18. The reverse osmosis system according to claim 17where said feed solution has a dissolved content of about from 0.005mg/L to about 20 mg/L As in the form of arsenic acid, and said permeatehas a dissolved arsenic content of less than about 1% of the initialcontent.
 19. The reverse osmosis system according to claim 17, wheresaid feed solution has a dissolved boron content of about 0.005 mg/L Bto about 20 mg/L B, and said permeate has a dissolved boron content ofless than about 50 to 20%, such as less than 25% of the initial content.20. The reverse osmosis system according to claim 17 where said feedsolution is an RO permeate from dairy waste water having a totalnitrogen content of from about 10 mg/L to 15 g/L N in the four of ureaor less, and said permeate has a total dissolved nitrogen content ofless than about 50% of the original content.
 21. The water extractionsystem for forward osmosis according to claim 9 further comprising areverse osmosis treatment of the diluted draw solution in the form of adraw solution recovery system (9), such as a reverse osmosis recoverywith reference to FIG. 5 herein.
 22. The water extraction systemaccording to any one of claims 1 to 8 for pressure retarded osmosis(PRO), wherein the non-feed side of the membrane functions as a drawside; and said water extraction system further comprising: f) means forproviding a draw solution in fluid communication with the draw side ofthe membrane, where said draw solution comprises natural sea or lakewater osmolytes and where said means comprises a closed volume whichallows for accumulation of pressure in the form of potential energy; g)means for providing a source solution to the feed side of said membrane,where said source comprises water having a higher water activity thansaid draw solution; and h) means for transforming said potential energyinto electricity, such as a turbine.
 23. The water extraction systemaccording to claim 22 where said draw solution is selected from saltwater sources, such as sea water, brackish water, soda lake water, deadsea water, saline solutions, and brine.
 24. The water extraction systemaccording to claim 22 or 23 where said source solution is obtained bydesalination of a draw solution and is produced by a surplus renewableenergy source.
 25. The water extraction system according to any one ofclaims 1 to 10 for reuse of used ultrapure water in a hemodialysisprocess, characterized in that used dialysate solution constitutes saidsource solution.
 26. The water extraction system according to claim 25further comprising the use of a concentrated fresh dialysate solution asa draw solution.